A new study links the March 2014 earthquakes in Poland Township, Ohio to hydraulic fracturing that activated a previously unknown fault. The induced seismic sequence included a rare felt earthquake of magnitude ...

Increased seismic activity raised concern Tuesday about the possibility of another eruption at a Japanese volcano where 36 people were killed, forcing rescuers to suspend plans to try to recover at least ...

Alaska's seismic network records thousands of quakes produced by glaciers, capturing valuable data that scientists could use to better understand their behavior, but instead their seismic signals are set aside as oddities. ...

In the global aftershock zone that followed the major April 2012 Indian Ocean earthquake, seismologists noticed an unusual pattern – a dynamic "stress shadow," or period of seismic silence when some faults near failure ...

(Phys.org) —Two Japanese companies, Mitsui Fudosan and Kajima Corp, have announced plans to install quake damping pendulums atop the Shinjuku Mitsui Building in downtown Tokyo by 2015. The building, like ...

An analysis of earthquakes in the area around the Salton Sea Geothermal Field in southern California has found a strong correlation between seismic activity and operations for production of geothermal power, which involve ...

The U.S. Geological Survey (USGS) and other scientific institutions are using social media and crowdsourcing to learn more about earthquakes, according to a new report. These techniques provide inexpensive and rapid data ...

Earthquake

An earthquake (also known as a tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacing the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

In its most generic sense, the word earthquake is used to describe any seismic event — whether a natural phenomenon or an event caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by volcanic activity, landslides, mine blasts, and nuclear experiments. An earthquake's point of initial rupture is called its focus or hypocenter. The term epicenter refers to the point at ground level directly above the hypocenter.